The changing face of unknown primary cancer of the head and neck (#37)
Metastatic carcinoma of the unknown primary is often associated with a poor prognosis. Metastatic squamous cell carcinoma (SCC) from an unknown primary of the head and neck forms a subset of patients with a more favourable outcome.
The most common parotid malignancy in Australia is metastatic SCC to intraparotid nodes (metastatic regional nodes) of skin origin. Approximately 10-15% will not have an identifiable index lesion. The management of these patients is surgery followed by post-operative radiotherapy. Cure rates are in excess of 80% with a very low (<5%) distant metastatic rate in immunocompotent patients.
Head and Neck cancers arising from mucosal sites such as the oropharynx and larynx have traditionally been associated with heavy smoking and drinking. Over the past decade there has been a substantial increase in HumanPapilloma Virus (HPV) associated oropharyngeal SCC, currently 70% in Australian centres. P16 staining of the tumour is used to identify HPV-associated disease. These tumours tend to present with small primary lesions, bulky neck nodes, in younger patients without necessarily a history of smoking. They are very responsive to chemo-radiotherapy with cure rates around 80-85%. An increasing number of these patients present with bulky nodes that are p16 positive with no identifiable disease.
There is now a new treatment paradigm for these patients which will be presented.